The invention relates to a return stop, comprising a rotating inner ring and a stationary, fixed outer ring, as well as a cage arranged between the inner ring and the outer ring with several roller pairs each consisting of two rollers, wherein at least one spring element is arranged between the two rollers of each roller pair for spring-loading the rollers at least against the outer ring, wherein a clamping ramp is formed on an outer peripheral surface of the inner ring for each roller of the respective roller pair.
The invention further relates to a transfer case for a motor vehicle, wherein this transfer case comprises such a return stop.
From the generally known prior art, transfer cases have become known that are equipped with coupling gear for setting a variable torque. The magnitude of the torque to be transferred by the coupling gear is here dependent on a clamping force of an actuator acting on the coupling gear. Usually the actuator is driven by an electric motor via a worm gear, in order to set the position of the coupling gear and thus the magnitude of the torque. The set position is then held by maintaining the power to the electric motor. One disadvantage is the resulting power consumption. Switching off the electric motor would be accompanied by a loss of the previously set position.
From DE 195 81 436 C1, a clamp-like locking device formed of a housing with an inner cylindrical clamping surface with drive elements and driven elements that can rotate relative to the housing and are arranged coaxial to the cylindrical clamping surface. The driven element is provided with clamping ramps that face the clamping surface and on which there are clamping roller pairs—formed from two clamping rollers following each other in the circumferential direction—whose two clamping rollers are spring-loaded away from each other by means of a spring element arranged between them against the clamping surface and the clamping ramps. Furthermore, the driven element is provided with stops for claws of the drive element, wherein these claws engage between two clamping roller pairs that are adjacent to each other. Here, the claws have, on their sides facing the stops, stops for each clamping roller of a clamping roller pair, wherein a circumferential clearance is formed between the stops and the claws that is greater than a circumferential clearance between the contacts and the clamping rollers. In addition, the driven element has a thin-wall sheet metal part that is drawn radially inward at multiple positions distributed around the circumference through the formation of recesses, wherein walls of the recesses arranged on the circumferential side form the stops and border plateaus provided with the clamping ramps on the circumferential side.